The present invention relates to systems which may have a limited power supply and more particularly to a method and system for providing intelligent power management that allows for step-down power conversion in such a system.
Many systems utilize a power supply which may have a limited capacity. For example, truck tractors, boats, golf carts, and satellites may utilize a battery or other energy storage apparatus for DC electrical power. These devices may have a mechanism for recharging the battery, such as an alternator. However, on occasion these devices operate on the stored power from the battery. For example, a truck tractor typically includes an alternator for generating power, a battery for storing power, and various subsystems which may consume power. These power consumers include a cranking system; lights; computers; communication devices electronics for the engine, brakes, steering and other subsystems; and comfort devices such as heating cooling, ventilation, refrigeration, microwaves, and televisions. Many of the power consumers can operate on the stored power of the battery alone when the alternator is not generating power.
Breakdown of the electrical system can be the primary cause of failure for many of these devices, such as the tractor trailer. Even where the electrical system is less subject to malfunctions, breakdown of the electrical system can cause the device to be unable to function. Such a failure of the device may be expensive, both to repair and in other costs absorbed by the user. For example, a failure of the electrical system which drains the battery of a truck tractor may be costly not only because the truck tractor must be towed to another location and repaired, but also because time and perishable cargo may be lost. Consequently, the ability to predict, diagnose, and avoid such failures is desirable.
Mechanisms for avoiding such failure are disclosed in U.S. Pat. No. 5,871,858 by Thomsen et al. (xe2x80x9cThomsenxe2x80x9d) and U.S. Pat. No. 5,798,577 by Lesesky et al. (xe2x80x9cLeseskyxe2x80x9d). Thomsen and Lesesky treat one problem that has been diagnosed in devices such as a truck tractor, the problem of overcranking. Consequently, Thomsen discloses cutting off power to the cranking system of a truck tractor when the current flowing and time for which the current flows exceed a particular level. Similarly, Lesesky discloses cutting off power to the cranking system of a truck tractor when a user has provided a cranking signal for greater than a particular time. Furthermore, Thomsen treats the problem of theft using solid state switches controlled using a micro-computer and a code input by a user. Based on whether a code is provided to the system, whether the internal temperature of a switch is above a particular value, and whether a particular current has been provided for a particular time, Thomsen allows power to be provided to the cranking motor.
However, it would still be desirable to be capable of diagnosing impending failures, avoiding failures, providing power to consumers in a more optimal manner. Accordingly, what is needed is a system and method for providing intelligent power management. The present invention addresses such a need.
A method and system for managing power in a device having a power source is described. The method and system comprise switches and at least one controller. The switch is coupled with the power source and a portion of the device. The at least one controller is coupled with the switch and is for controlling the switch to be open or closed based on instructions provided to the controller. The controller toggles the switch to provide pulse-width modulation, thereby stepping-down a first power to a desired power provided to the portion of the device. In another aspect, the method and system comprise loading software for providing pulse width modulation in at least one controller of a system. The system includes at least one switch coupled with the power source, a portion of the device and the controller. In this aspect, the method and system also comprise utilizing the at least one controller for toggling the switch to provide pulse-width modulation based on the software. Thus, a first power is stepped down to a desired power provided to the portion of the device.
According to the system and method disclosed herein, the present invention allows power to different subsystems to be stepped down. As a result, the desired power can be provided to particular subsystems, improving the operation of subsystems of the device, such as the battery.